Twin-wire papermaking machine with suction boxes within the loop of one wire and blast boxes within the other

ABSTRACT

A twin-wire papermaking machine which includes a dewatering and press section, the dewatering section employing suction boxes within the loop of one of the forming wires, and blast boxes within the loop of the other forming wire. The boxes have convex domes which cause the two wires to move in a serpentine configuration and are positioned to provide continuous support thereto. The dewatering section may also employ opposed foils, press cylinders, and suction cylinders located opposite to grooved cylinders.

F. ARLEDTER 3,810,818

ES WITHIN-THE AND BLAST BOXES WITHIN THE OTHER May 14, 1974 TWIN-WIRE PAPERMAKING MACHINE WITH sucnon BOX LOOP OF ONE WIRE Filed Oct. 26, 1971 3 Sheets-Sheet 1 y 14, 1974 H. F. ARLEDTER 3,

TWIN-WIRE PAPERMAKING MACHINE WITH SUCTION BOXES WITHIN THE OOP OF ONE WIRE AND BLAST BOXES WITHIN THE OTHER Filed Oct. 26, 1971 5 Sheets-Sheet 2 y 14, 1974 H. F. ARLEDTER 3,810,818 7 TWIN-WIRE PAPERMAKING MACHINE WITH SUCTION BOXES WITHIN THE LOOP OF ONE WIRE AND BLAST BOXES WITHIN THE OTHER Filed Oct. 26, 1971 5 Sheets-Sheet 3 United States Patent 3,810,818 TWIN-WIRE PAPERMAKING MACHINE WITH SUC- TION BOXES WITHIN THE LOOP OF ONE WIRE AND BLAST BOXES WITHIN THE OTHER Hanns F. Arledter, 122 Andritzer Reichsstrasse, 8046 Graz St. Veit, Austria Filed Oct. 26, 1971, Ser. No. 192,276

Claims priority, application Austria, Oct. 30, 1970,

9,763/ 70 Int. Cl. D211? 1/00, N52

US. Cl. 162-301 13 Claims ABSTRACT OF THE DISCLOSURE A twin-wire papermaking machine which includes a dewatering and press section, the dewatering section employing suction boxes within the loop of one of the forming wires, and blast boxes within the loop of the other forming wire. The boxes have convex domes which cause the two wires to move in a serpentine configuration and are positioned to provide continuous sup-port thereto. The dewatering section may also employ opposed foils, press cylinders, and suction cylinders located opposite to grooved cylinders.

BACKGROUND OF THE INVENTION The invention relates to a papermaking machine having a sheet formation area, a wire section for pre-dewatering of said sheet, and a press section for further dewatering of said sheet.

With the known papermaking machine, sheet formation and pre-dewatering of the sheet take place in a first wire section. From this section, the pre-dewatered sheet is then transferred to the wire of a press section for further dewatering. In said first wire section a percentage of solids in the sheet is attainable up to 15 to 25% (solids/solids plus liquid); in the press section the percentage of solids attainable is up to 35 to 44% The purpose of the invention is to improve the dewatering effect in respect of said pre-dewatering and further dewatering. According to the invention, the sections for predewatering and further dewatering are combined to form a common double wire section, between the wires of which the sheet to be dewatered is held, and said double wire section has as dewatering elements, boxes with a perforated convex domed wire-supporting wall, and at least two further elements selected from the group of elements comprising foils, suction cylinders, press cylinders, grooved cylinders, and the like. Said boxes are settable under pressure differing from the pressure of the atmosphere and can serve as suction boxes for draining liquid from the sheet, or as blast boxes for blowing hot air, for example, against the sheet. The suction box domes engage one wire while the blast box domes engage the other wire. A plurality of the blast and suction boxes are arranged one after the other and in close proximity to one another throughout a region of the double wire section.

Because of the wire being held closely on the box, said boxes allow, when serving as suction boxes, vacua up to 8 to 9 in. water column. By combining said boxes with the known dewatering devices such as foils, suction cylinders, press cylinders, grooved cylinders, Manchon cylinders, and by using the per se known double wire arrangement for the new combination, surprisingly good dewatering effect is achieved with the invention. The result is that said pre-dewatering and further dewatering can take place in a common section and need less room than hitherto.

Advantageously, the dewatering elements are so controlled as to reach a percentage of solids in sheet of 40% or more.

If a lower percentage is sufiicient the dewatering elements can be so controlled as to reach a percentage of solids in the sheet of 25% or more. In this case, number and/or space of the dewatering elements can be reduced.

Extremely good dewatering efiect takes place if the dewatering elements, especially the boxes with convex domed wall, are so arranged as to lead the wires of the double wire section in form of a serpentine. The thereby resulting centrifugal forces can be used for the dewatering. In the serpentine, a part of the boxes with convex domed wall can serve as suction boxes, while other boxes blow air under pressure against the double wire.

Furthermore, it is of advantage to have arranged the dewatering elements as close to each other as possible, whereby the boxes with convex domed wall are very helpful.

An extremely compact papermaking machine has the double wire section with two wires only, and sheet formation on one or both of said two wires before these wires join into the double section.

BRIEF DESCRIPTION OF THE DRAWING In the drawing, with the help of which the invention is described in detail, embodiments of the invention are shown in simplified manner.

FIG. 1 shows a vertical section, in the direction of wire travel, through the papermaking machine for sheet formation, pre-dewatering and further dewatering,

FIG. 2 a corresponding vertical section through another machine, and

FIG. 3 shows a corresponding vertical section through a further machine.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiment shown in FIG. 1 has two wires 1 and 2 which join into a double wire section 3. The sheet formed in a sheet formation area 4 is lead between the wires 1 and 2 of the section 3 and is pre-dewatered and further-dewatered in said section 3. Sheet formation takes place in the area 4 and area 3 is a dewatering zone. The double wire section 3 has, as dewatering elements, stationary boxes 5, 6, 7, 8 with a perforated convex domed wall supporting one of said wires 1 or 2 respectively. As further dewatering elements, in the double wire section there are arranged foils 9 and 10, press cylinders 11, a grooved cylinder 12 co-operating with a suction cylinder 13, a suction cylinder 14 co-operating with a press cylinder 15. For picking up the dewatered sheet from the wire 2 a pick-up roller 16 is arranged on said wire.

In the double wire section 3 common for both pre-dewatering and further dewatering of the sheet, the latter is brought to a percentage of solids of at least 40%. Percentages of solids of 50% and more can be achieved.

The boxes 5 through 8 with convex domed wall, the grooved cylinder 12 and the suction cylinder 13, as well as the suction cylinder 14 and the press cylinder 15 are so arranged as to lead the wires 1 and 2 in the double wire section 3 in form of a serpentine. The boxes 6 and 8 are set under a lower pressure than the pressure of the atmosphere, and serve as suction boxes, while the boxes 5 and 7 are set under a higher pressure than the pressure of the atmosphere and fed with compressed air. The boxes for suction alternate, in the direction of wire travel, with the boxes for compressed air.

Most of the dewatering elements, i.e. the foils 9, 10 and the boxes 5, 6, 7 and 8 immediately succeed each other in the direction of wire travel. Equally, the pairs of pressing cylinders, i.e. the cylinders 12 and 13 as well as 14 and 15, follow the suction box 8 and each other very closely.

The grooved cylinder 12 has a diameter of mm., and the co-operating suction cylinder 13 has a greater diameter (more than 150 mm.). This cylinder 13 also serves for the wire drive.

By arranging all of the dewatering elements for predewatering and further dewatering in the common section 3 with the two wires 1 and 2, the machine is very compact. Sheet formation takes place in the region where the same wires 1 and 2 join into section 3.

The sheet leaving the compact machine at the pick-up roller \16 is completely dewatered so that it can be directly transferred to the drying cylinders of the drier section of the papermaking machine. That is to say, the sheet leaving this compact machine does not pass through a separate press section before transfer to the drying section.

With the embodiment according to FIG. 2, one of the two wires of the double wire section 3 is subdivided, in the direction of wire travel, into wires 1 and 1 The first part of the section 3 with the wire 1 runs vertically, the second part with the wire 11 runs horizontally.

The wire 1 travels over a drying cylinder 17 fed with hot air and is thus dewatered. Dewatering of the wires can also be secured by foils, brush cylinders, suction gaps, webs, and the like.

In the region where the two wires 1 and 2 join into the double wire section a sheet forming area 4 is arranged. The latter is followed, in direction of wire travel, by foils 18, boxes 19 with convex domed wall, and, in the region where the wire 1 leaves the wire 2, a blast cylinder 20. This blast cylinder 20 presses the sheet onto the wire 2 which takes the sheet into the second part of the section B. At the beginning of said second part a suction cylinder 22 co-operating with a press cylinder 21 is arranged. In direction of wire travel, the cylinders 21, 22 are followed by a box 23 with convex domed wall, serving as suction box, then a suction cylinder 25 co-operating with a grooved cylinder 24, next by a box 26 with convex domed wall, serving as blast box and co-operating with a suction box 27 with concave wall surface, and finally two press cylinders 28. The sheet leaving the section 3 at the cylinders 28 is completely dewatered and can be directly transferred to the drying cylinder of a drier section.

In the double wire section 3 of the embodiment according to FIG. 3, foils 29, three boxes 30 with convex domed wall, a suction cylinder 32 co-operating with a grooved cylinder 31, two boxes 33 with convex domed wall, and a suction cylinder 35 co-operating with a press cylinder 34 follow each other in the direction of wire travel. The sheet leaving the section 3 is transferred, by a pick-up roller 36, to a wire 37 which travels over a heavy-duty drying cylinder '38. The dried sheet is picked-up by a pickup cylinder 39.

With all three embodiments shown in the drawing, sheet formation takes place with a bath of suspension, said bath being supported by the two wires in the region where the latter join into the double wire section. Thereby, suction boxes are arranged under that part of the wire, that supports the bath.

The cylinders or rollers for the wire drive can be arranged outside the double section of the wires. However, in order to maintain the wire tension low in spite of the many dewatering elements, the inventor arranges one or more driving cylinders within the double wire section. With the embodiment according to FIG. 1, besides the suction cylinder 13 the press cylinder 11. could be driven too. With the embodiment according to FIG. 2, the two suction cylinders at the entrance of section 3, the cylinders 21, 22, 24, 25 or 28 could be driven. With the embodiment according to FIG. 3 the cylinders 31, 32, 34 or '35 could serve for the wire drive.

Under papermaking machine is also understood, in the sense of the invention, a machine which produces a paper-like sheet, for example non-woven webs. Under wire are also understood other webs for the transport or dewatering of the sheet to be dewatered, for example felts.

I claim:

1. A combined dewatering and press section for a papermaking machine, comprising:

(a) coacting, traveling, looped wire means having juxtaposed sections which define a double wire section and confine a fiber web therebetween, at least the initial portion of said double wire section being vertical, said double wire section including both a dewatering and a press section;

(b) a headbox receptacle for a liquid suspension of fibers;

((1) means guiding one of said looped wire means along a wall of said receptacle whereby fibers are deposited thereon from said suspension to form said fiber web;

(d) a series of boxes, in said double wire section having convex, domed wire-supporting surfaces, the series consisting of suction boxes and blast boxes, every other box being a suction box and the remaining boxes being blast boxes, the domed surfaces of the suction boxes engaging the outer face of one wire means and the domed surfaces of the blast boxes engaging the outer face of the other wire means, the domed surfaces providing a continuous support for said wire means whereby the double wire section is serpentine in the region of said series of boxes;

(e) foil means engaging the outer faces of said wire means in said double wire section; and

(f) coacting, rotating cylinders in said double wire section and between which said wire means pass.

2. The combination defined in claim 1 including: (a) a plurality of press cylinders; and at least one suction cylinder in one of said pairs.

3. The combination defined in claim 2; and

(a) a second of said pairs of press cylinders includes a suction cylinder and a coacting grooved cylinder.

4. The machine definedin claim 3 in which (a) the suction cylinder of the second pair is a driving cylinder, and

(b) has a larger diameter than said grooved cylinder.

5. The combination defined in claim 2 in which one of said cylinders is a Manchon cylinder.

6. The combination defined in claim 2 in which said suction cylinder is a Manchon cylinder.

7. The machine defined in claim 1; and

(a) at least one driving cylinder in said double wire section.

8. The machine defined in claim 7 in which (a) said driving cylinder is a suction cylinder.

9. The combination defined in claim 1 in which (a) the second looped wire means is also guided across a bottom wall of said receptacle to provide additional web-forming area, and

(b) said wire means being so guided through said receptacle as to converge toward one another and, at the point of their closest approach and at the bottom of said receptacle, define the beginning of said double wire press and dewatering section.

10. The combination defined in claim 1 in which:

(a) one of said looped wire means comprises two endless, looped Wires, one endless wire forming a first part of said double wire section and the other endless wire forming a second part of the double wire section; and

(b) the other wire means comprises a single endless wire loop.

11. The combination defined in claim 10 in which (a) said first part of the double wire section runs vertically, and

(b) said second part runs horizontally.

12. The machine defined in claim 1; and

(a) a dewatering device effective to remove water from one of said wire means at a point in the loop removed from said double wire section.

13. The combination defined in claim 1; and

5 6 (a) a press roll acting to urge said wires and the web 3,471,367 10/1969 Chupka 162-203 X confined therebetween toward the domed surface of 2,141,393 12/1938 Hutchins 162--203 FOREIGN PATENTS References Cited 5 246,048 1/ 1926 Great Britain 162--203 UNITED STATES PATENTS OTHER REFERENCES RE 25 3 33 2 1953 Baxter 1 2 2 3 X :Handbuck de Papier-und Pappenfabrikation (Papier- 3,578,561 5/1971 McCarrick et a1. 162--352 lexlkon),1961,pp-591592, 1163-1165- 1,241,905 10/1917 Behr 100-153 X 3,438,854 4/1969 Means 162 374 X 10 S. LEON BASHORE, Pnmary Examiner 3,403,073 9/1968 Moran 162-203 R. H. TUSHIN, Assistant Examiner 3,087,538 4/1963 Newman 162-297 U S Cl X R 3,291,680 12/1966 Justus et a1 162-274 X 3,573,161 3/1971 Notbohm 1 62--203 X 15 162203, 208, 308, 303 

